Detox - minimalistic respin of toxic.

This client based on Toxic and meant to be smaller, lighter,
less dependencies, no bells and whistles, no HTTP(s) requests,
trying to be as decentralized as possible w/o relying on centralized
entities, etc.

Idea behind this respin it would try to be decentralized and respecting
user's privacy. I.e. no phoning home to certain centralized hosts or
something.

It comes at price: less "misc" features unrelated to text mode chats.

Goals of THIS fork:
- Simplicity.
- Privacy.
- Decentralization.
- Security.
- Minimal dependencies.
- Runs on Linux.

+++ Now it got integrated Toxcore to ensure its dead simple to build
    It needs libc6-dev, libconfig-dev, libsodium-dev, libncurses-dev
    and working C compiler. Not so much, eh?

In details:
- More dumb build system - also easier to grasp and tweak.
    * No longer stands on the way if e.g. trying to link to
        custom-built Tox core that isn't "installed" etc.
    * As result it no longer depends on pkgconfig.
- Sizably less dependencies.
    * No longer needs librurl, it got totally nuked.
    * No longer needs pkgconfig to build.
    * Minimal toxcore is enough, no AV support needed.
    * Only needs toxcore, libsodium, ncursesw and libconfig
- Smaller code.
    * Audio/video entorely removed.
       Less code, less libs: security++. No voice/video leaks, privacy++.
       FIXME: grok through code and check it behaves.
       FIXME: further uncruft code of dead ifdefs.
    * Python & API removed. Leave it to bots or something.
        Less ways to shoot legs, less libs: privacy++, security++.
    * Games removed. Why should it be part of chat?
        Less code, less complexity, security++
    * X11 support removed. Its odd for text mode program.
        As side effects, X11 never been created with security
          in mind. Nor it can track activity anymore. Privacy++, security++.
    * QR codes removed so no deps on png or QR libs.
    * Notify libs removed, no deps on audio or notify libs.

Approx changelog - filled as codewalk progressed:
- Removed support of:
  * Games. Less code == less bloat and cruft.
  * Audio. This respin is minimal text mode only.
  * Video. This respin is minimal text mode only.
  * X11. Doesn't belongs text mode programs.
  * Python. Use toxic if you need bells and whistles.
  * No QR-related things, its overkill.
  * No audio/desktop notification - so no annyoances.
  * Nuked libcurl dep. P2P isnt web:
    * Deleted stupid bootstrap node DL. Centralized, violates
        privacy by reporting client to central server.
    * Nuked wtf name "lookup" thing. Doesn't belongs P2P.
  * No CI, etc. This thing going to support Linux as I cant test it
     reasonably on mac or windows, nor their users prefer terminals.
  * No Google bazel crap, use toxic or something if you need android,
     Android suxx in privacy anyway.
  * Initial commit should be done, it builds.